1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2013-2015 ARM Limited, All Rights Reserved.
4  * Author: Marc Zyngier <marc.zyngier@arm.com>
5  */
6 
7 #include <linux/acpi_iort.h>
8 #include <linux/pci.h>
9 #include <linux/msi.h>
10 #include <linux/of.h>
11 #include <linux/of_irq.h>
12 #include <linux/of_pci.h>
13 
14 static void its_mask_msi_irq(struct irq_data *d)
15 {
16 	pci_msi_mask_irq(d);
17 	irq_chip_mask_parent(d);
18 }
19 
20 static void its_unmask_msi_irq(struct irq_data *d)
21 {
22 	pci_msi_unmask_irq(d);
23 	irq_chip_unmask_parent(d);
24 }
25 
26 static struct irq_chip its_msi_irq_chip = {
27 	.name			= "ITS-MSI",
28 	.irq_unmask		= its_unmask_msi_irq,
29 	.irq_mask		= its_mask_msi_irq,
30 	.irq_eoi		= irq_chip_eoi_parent,
31 };
32 
33 static int its_pci_msi_vec_count(struct pci_dev *pdev, void *data)
34 {
35 	int msi, msix, *count = data;
36 
37 	msi = max(pci_msi_vec_count(pdev), 0);
38 	msix = max(pci_msix_vec_count(pdev), 0);
39 	*count += max(msi, msix);
40 
41 	return 0;
42 }
43 
44 static int its_get_pci_alias(struct pci_dev *pdev, u16 alias, void *data)
45 {
46 	struct pci_dev **alias_dev = data;
47 
48 	*alias_dev = pdev;
49 
50 	return 0;
51 }
52 
53 static int its_pci_msi_prepare(struct irq_domain *domain, struct device *dev,
54 			       int nvec, msi_alloc_info_t *info)
55 {
56 	struct pci_dev *pdev, *alias_dev;
57 	struct msi_domain_info *msi_info;
58 	int alias_count = 0, minnvec = 1;
59 
60 	if (!dev_is_pci(dev))
61 		return -EINVAL;
62 
63 	msi_info = msi_get_domain_info(domain->parent);
64 
65 	pdev = to_pci_dev(dev);
66 	/*
67 	 * If pdev is downstream of any aliasing bridges, take an upper
68 	 * bound of how many other vectors could map to the same DevID.
69 	 * Also tell the ITS that the signalling will come from a proxy
70 	 * device, and that special allocation rules apply.
71 	 */
72 	pci_for_each_dma_alias(pdev, its_get_pci_alias, &alias_dev);
73 	if (alias_dev != pdev) {
74 		if (alias_dev->subordinate)
75 			pci_walk_bus(alias_dev->subordinate,
76 				     its_pci_msi_vec_count, &alias_count);
77 		info->flags |= MSI_ALLOC_FLAGS_PROXY_DEVICE;
78 	}
79 
80 	/* ITS specific DeviceID, as the core ITS ignores dev. */
81 	info->scratchpad[0].ul = pci_msi_domain_get_msi_rid(domain, pdev);
82 
83 	/*
84 	 * Always allocate a power of 2, and special case device 0 for
85 	 * broken systems where the DevID is not wired (and all devices
86 	 * appear as DevID 0). For that reason, we generously allocate a
87 	 * minimum of 32 MSIs for DevID 0. If you want more because all
88 	 * your devices are aliasing to DevID 0, consider fixing your HW.
89 	 */
90 	nvec = max(nvec, alias_count);
91 	if (!info->scratchpad[0].ul)
92 		minnvec = 32;
93 	nvec = max_t(int, minnvec, roundup_pow_of_two(nvec));
94 	return msi_info->ops->msi_prepare(domain->parent, dev, nvec, info);
95 }
96 
97 static struct msi_domain_ops its_pci_msi_ops = {
98 	.msi_prepare	= its_pci_msi_prepare,
99 };
100 
101 static struct msi_domain_info its_pci_msi_domain_info = {
102 	.flags	= (MSI_FLAG_USE_DEF_DOM_OPS | MSI_FLAG_USE_DEF_CHIP_OPS |
103 		   MSI_FLAG_MULTI_PCI_MSI | MSI_FLAG_PCI_MSIX),
104 	.ops	= &its_pci_msi_ops,
105 	.chip	= &its_msi_irq_chip,
106 };
107 
108 static struct of_device_id its_device_id[] = {
109 	{	.compatible	= "arm,gic-v3-its",	},
110 	{},
111 };
112 
113 static int __init its_pci_msi_init_one(struct fwnode_handle *handle,
114 				       const char *name)
115 {
116 	struct irq_domain *parent;
117 
118 	parent = irq_find_matching_fwnode(handle, DOMAIN_BUS_NEXUS);
119 	if (!parent || !msi_get_domain_info(parent)) {
120 		pr_err("%s: Unable to locate ITS domain\n", name);
121 		return -ENXIO;
122 	}
123 
124 	if (!pci_msi_create_irq_domain(handle, &its_pci_msi_domain_info,
125 				       parent)) {
126 		pr_err("%s: Unable to create PCI domain\n", name);
127 		return -ENOMEM;
128 	}
129 
130 	return 0;
131 }
132 
133 static int __init its_pci_of_msi_init(void)
134 {
135 	struct device_node *np;
136 
137 	for (np = of_find_matching_node(NULL, its_device_id); np;
138 	     np = of_find_matching_node(np, its_device_id)) {
139 		if (!of_device_is_available(np))
140 			continue;
141 		if (!of_property_read_bool(np, "msi-controller"))
142 			continue;
143 
144 		if (its_pci_msi_init_one(of_node_to_fwnode(np), np->full_name))
145 			continue;
146 
147 		pr_info("PCI/MSI: %pOF domain created\n", np);
148 	}
149 
150 	return 0;
151 }
152 
153 #ifdef CONFIG_ACPI
154 
155 static int __init
156 its_pci_msi_parse_madt(union acpi_subtable_headers *header,
157 		       const unsigned long end)
158 {
159 	struct acpi_madt_generic_translator *its_entry;
160 	struct fwnode_handle *dom_handle;
161 	const char *node_name;
162 	int err = -ENXIO;
163 
164 	its_entry = (struct acpi_madt_generic_translator *)header;
165 	node_name = kasprintf(GFP_KERNEL, "ITS@0x%lx",
166 			      (long)its_entry->base_address);
167 	dom_handle = iort_find_domain_token(its_entry->translation_id);
168 	if (!dom_handle) {
169 		pr_err("%s: Unable to locate ITS domain handle\n", node_name);
170 		goto out;
171 	}
172 
173 	err = its_pci_msi_init_one(dom_handle, node_name);
174 	if (!err)
175 		pr_info("PCI/MSI: %s domain created\n", node_name);
176 
177 out:
178 	kfree(node_name);
179 	return err;
180 }
181 
182 static int __init its_pci_acpi_msi_init(void)
183 {
184 	acpi_table_parse_madt(ACPI_MADT_TYPE_GENERIC_TRANSLATOR,
185 			      its_pci_msi_parse_madt, 0);
186 	return 0;
187 }
188 #else
189 static int __init its_pci_acpi_msi_init(void)
190 {
191 	return 0;
192 }
193 #endif
194 
195 static int __init its_pci_msi_init(void)
196 {
197 	its_pci_of_msi_init();
198 	its_pci_acpi_msi_init();
199 
200 	return 0;
201 }
202 early_initcall(its_pci_msi_init);
203